Electrical connector testing apparatus having a plurality of and gates

ABSTRACT

The present invention provides method and apparatus for testing electrical connector apparatus. Preferably, the apparatus is arranged to test a plurality of connectors, and comprises a plurality of sets of apparatus as hereinafter set out, a counter, means responsive to the counter for applying in turn the signal to the first terminal of each of the sets, a single indicator connected to the outputs of all the AND gates, and means responsive to the counter for sampling the indicator during each count and stopping the counter when no output from the appropriate AND gate is received.

mte States a t 11 1 1111 3,795,5'7 Brown Mar. 5, 1974 ELECTRICALCONNECTOR TESTING 3,286,175 11/1966 Gerbier et a1 324/73 R APPARATUSHAVING A PLURALITY 0F 3,495,172 2/1970 Davis l 324/51 3,689,830 9/1972Caldwell et al. 324/51 AND GATES Primary ExaminerGerard R. Strecker [57]ABSTRACT The present invention provides method and apparatus for testingelectrical connector apparatus. Preferably, the apparatus is arranged totest a plurality of connectors, and comprises a plurality of sets 01apparatus as hereinafter set out, a counter, means responsive to thecounter for applying in turn the signal to the first terminal of each ofthe sets, a single indicator connected to the outputs of all the ANDgates, and means responsive to the counter for sampling the indicatorduring each count and stopping the counter when no output from theappropriate AND gate is received.

1 Claim, 3 Drawing Figures PAIENIEDHAR 51974 3,795,857

sum 1 nr 2 ml H FIG.

I I l I I l I I 27 II I I I I I I I I 25 CO J I I I I I 1 I 27 25 2-";

FIG. 3

ELECTRICAL CONNECTOR TESTING APPARATUS HAVING A PLURALITY OF AND GATESThis invention relates to testing apparatus for electrical connectors.

According to the invention there is provided electrical connectortesting apparatus comprising an AND gate, an indicator connected to theoutput of the AND gate, first and second terminals to which the ends ofthe connectors can be attached, the first and second terminals beingconnected respectively to the first and second inputs of the AND gate,means for applying a signal to the first terminal, and means biasing thesecond terminal so that in the absence of a signal' applied through theconnector to the second terminal from the first terminal no signalappears at the second input of the AND gate.

The invention also includes a method of testing electrical connectorscomprising connecting the two ends of the connectors to separate inputsof an AND gate, applying a signal to one end of the connector andbiasing the other end of the connector so as to switch the AND off inthe absence of the signal applied to said other end through theconnector, and indicating the absence of a signal from the output of theAND gate.

Preferably, the apparatus is arranged to test a plurality of connectors,and comprises a plurality of sets of apparatus as set out above, acounter, means responsiveto the counter for applying in turn the signalto the first terminal of each of the sets, a single indicator connectedto the outputs of all the AND gates, and means responsive to the counterfor sampling the indicator during each count and stopping the counterwhen no output from the appropriate AND gate is received.

Preferably, means are provided for biasing off the first terminals ofeach set, and conveniently the same biasing means may be provided forbiasing off both terminals of one set. Further indicator means may beconnected to the first terminals of all the sets, and responsive to biascurrent from the common biasing means in order to indicate a shortcircuit between one connector and another.

An example of the invention will now be described with reference to theaccompanying drawings, in which:

FIG. 1 illustrates the basic circuit testing element;

FIG. 2 shows a decade tester incorporating ten basic elements; and

FIG. 3 shows how a multi-end connector is connected into the testingcircuit.

The basic circuit testing element is shown in FIG. 1 and comprises twoterminals 11, 12 for connection to the ends of the connector 13 to betested. Each terminal is connected through its own load resistor 14, 15to a positive potential 16. Each terminal is connected through its owndiode 17, 18 and by a common resistor 19 to the base of a sensingtransistor 21. One terminal 11 is connected through an activatingtransistor and current sensing resistor 23 to a negative potential 24.

In operation, an activating signal is applied on the base of theactivating transistor 25 to switch it on, thus biasing the firstterminal 11 negatively. If the connector 13'across the two terminals 11,12 is continuous, the second terminal 12 will also be biassednegatively. When both terminals 11, 12 are negatively biassed, thesensing transistor 21 is switched off, but if only one terminal isnegatively biassed, the transistor 21 remains on. The transistor 21 issampled during each test, and if the transistor is on, a continuityfault is indicated.

FIG. 2 shows ten basic elements connected for testing ten two-endedconnectors in succession. The resistor 23a connecting the activatingtransistors to the negative potential 24 is common to all sets and acommon indicating transistor TR22 is connected to the outputs of thesensitizing transistor 21 (referenced TRl 1-20 in FIG. 2). The terminals2428 and 42 to 46 correspond to the first terminal 11; the terminals 30to 34 and 48 to 52 correspond to the biasing terminals 16; the terminals36 to 40 and 54 to 58 correspond to the second terminals 12; resistorsR1 1-R20 correspond to the load resistors 14; resistors R21-R30correspond to the load resistor 15; the diodes D31-D4l) correspond tothe diode 17; the diodes D41-D50 correspond to the diode 18; theresistors R41-R50 correspond to the resistor 19; the transistorsTRllll-TRZt) correspond to the sensing transistor 21; the transistorsTRl-TRN) correspond to the activating transistor 25. The diodes D21-D30and resistors REL-R40 form part of a test circuit which does not formpart of the invention.

A decade counter is used to apply an activating signal in turn to theactivating transistors 25 through input terminals (L9 and the samecounter is used to sample the output of the indicating transistor TR22through examining means while each activating signal is applied. Thecounter 80 is also arranged to display the number of the connector undertest and to stop counting when examining means 85 senses that theindicatingtransistor TR22 is switched on by one sensing transistor 21failing to switch off, so that the stopped counter 80 displays thenumber of the faulty connector.

When there is a cross connection between connectors under test,thecurrent sensing resistor 23a will carry a greater current than thatdue to the flow through the load resistors 14, '15 of the two terminals11, 12 of the connector under test as it will also carry the currentfrom the load resistor or resistors connected to the connector to whichthere is a cross connection. A circuit connected to the current sensingresistor at output 26 senses the increased current and stops the test,indicating a cross-connection fault.

When a cross-connection is intended to be present between connectorsunder test, that is when a connector has three or more ends, the thirdand any subsequent ends are connected to the first terminals of furtherelements in the circuit. FIG. 3 illustrates a four end connector, whichuses three basic elements. End A is connected to the second terminal ofone element and ends B, C and D to the first terminals of the oneelement and two further elements respectively. Continuity is tested inturn between B and A, C and A, and D and A. The positive potential isremoved from terminals 16 in the further elements so that there is noincreased current flow in the current sensing resistor 23 due to thecross connections between elements indicating a short circuit fault. Inorder to prevent an open circuit indication, a connection 27 is madebetween the second terminals of all the elements to which the multiendconnector is connected so that each sensing transistor can be turned offif there is continuity between the appropriate first terminal and theone second terminal to which the connector is connected.

What we'claim is:

1. Electrical connector testing apparatus comprising,

a plurality of first and second test terminals to which the ends of aconnector to be tested can be attached,

a plurality of AND gates each having first and second input terminalsconnected to respective ones of said plurality of first and second testterminals, each AND gate having an output terminal at which a signalwill be present only when a signal is present at both input terminals ofsaid each AND gate,

counting means,

means responsive to said counting means for applying in turn a signal tothe first input terminal of each AND gate,

first biasing means for biasing the first input terminals of each ANDgate so that a signal will only appear at each of the first inputterminals of each AND gate when a signal is applied by the signalapplying means to the first terminal,

second biasing means for biasing the second input terminals of saidplurality of AND gates so that a signal will only appear at each of thesecond input terminals of each AND gate when a conductive path ispresent between the first and second test terminals connected to saideach AND gate and said signal applying means applies a signal to therespective first input terminal,

a first indicating means connected to the output terminals of all saidAND gates for providing a signal when any of said AND gate outputterminals has a signal thereon,

means responsive to said counting means for examining said firstindicating means signal during each count and stopping said countingmeans when no first indicating means signal is present, the count atwhich said counting means is stopped being an indication of whichconnector has an open circuit, and

a second indicating means connected to the first input terminals of allsaid AND gates and responsive to a current greater than that normallyflowing to any single first input terminal from said first biasing meansto indicate a cross connection between tWO connectors.

1. Electrical connector testing apparatus comprising, a plurality offirst and second test terminaLs to which the ends of a connector to betested can be attached, a plurality of AND gates each having first andsecond input terminals connected to respective ones of said plurality offirst and second test terminals, each AND gate having an output terminalat which a signal will be present only when a signal is present at bothinput terminals of said each AND gate, counting means, means responsiveto said counting means for applying in turn a signal to the first inputterminal of each AND gate, first biasing means for biasing the firstinput terminals of each AND gate so that a signal will only appear ateach of the first input terminals of each AND gate when a signal isapplied by the signal applying means to the first terminal, secondbiasing means for biasing the second input terminals of said pluralityof AND gates so that a signal will only appear at each of the secondinput terminals of each AND gate when a conductive path is presentbetween the first and second test terminals connected to said each ANDgate and said signal applying means applies a signal to the respectivefirst input terminal, a first indicating means connected to the outputterminals of all said AND gates for providing a signal when any of saidAND gate output terminals has a signal thereon, means responsive to saidcounting means for examining said first indicating means signal duringeach count and stopping said counting means when no first indicatingmeans signal is present, the count at which said counting means isstopped being an indication of which connector has an open circuit, anda second indicating means connected to the first input terminals of allsaid AND gates and responsive to a current greater than that normallyflowing to any single first input terminal from said first biasing meansto indicate a cross connection between two connectors.